Digital Quartz Watches; Analog Watches - Casio PRT-40C Repair Manual

1-2 Digital Quartz Watches

Power Unit (Battery):
There are two types of batteries: a battery/lithium (3.0 V, mainly used in digital watches), and a battery/
silver oxide (1,55V, mainly used in analog watches). In addition, since the driving voltage of the LCD
driver is 3 V and that of the oscillator is 1.5 V, a voltage halver (for the oscillator) is provided in the LSI
of the modules using a battery/lithium, while a voltage doubler (for driving the LCD) is provided in the
LSI of the modules using a battery/silver oxide.
Oscillator:
This circuit generates a 32,768 Hz signal with the oscillator/quartz and capacitor/trimmer.
Frequency divider:
This circuit converts the 32,768 Hz signals produced with the oscillation circuit to 1 Hz signals with
Count Down Flip Flop.
Counter (memory):
This circuit controls the counting of time, calendar and stopwatch functions, etc. based on the 1 Hz
signals produced by the dividing circuit.
Driver:
This circuit drives the LCD, alarm, EL and so forth.
DIGITAL QUARTZ WATCH
Fig. 1-2

1-3 Analog Watches

Oscillator and Frequency divider:
These circuits function in the same manner as in digital watches.
Coil driver:
This circuit provides a 1 Hz alternating current (signal) to the coil of the analog block.
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